浙西底本剖面皮园村组硅质岩元素地球化学特征及成因分析  

Geochemistry and Genetic Analysis of Chert of the Piyuancun Formation in Western Zhejiang

作　　者：袁余洋 蔡春芳[2] 刘永林[3] 罗伟 唐晔 YUAN Yuyang;CAI Chunfang;LIU Yonglin;LUO Wei;TANG Ye(College of Resources and Environment,Zunyi Normal University,Zunyi 563006,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;School of Geography and Tourism,Chongqing Normal University,Chongqing 401331,China)

机构地区：[1]遵义师范学院资源与环境学院,遵义563006 [2]中国科学院地质与地球物理研究所,北京100029 [3]重庆师范大学地理与旅游学院,重庆401331

出　　处：《高校地质学报》2022年第4期516-526,共11页Geological Journal of China Universities

基　　金：国家自然科学基金(41602124,41502329);国家重点基础研究发展计划(2011CB808805,2014CB238906);贵州省自然科学基金(黔科合基础-ZK[2021]一般204);贵州省教育厅基金(黔教合KY字[2020]100);遵义师范学院博士基金项目(尊师BS[2018]07号)联合资助。

摘　　要：埃迪卡拉—寒武纪(Ediacaran-Cambrian,E-C)过渡时期在下扬子地区沉积了一套层状黑色硅质岩,在浙西底本剖面称为皮园村组,大致对应于上扬子地区的留茶坡组或老堡组。该套硅质岩普遍具有高有机碳含量和强烈富集铀(U)、钒(V)、钼(Mo)等氧化还原敏感元素的特征,与早寒武世沉积的黑色泥岩共称为黑色岩系,其成因存在争议。文章对浙西地区皮园村组硅质岩开展了系统的主量、微量和稀土元素地球化学研究,探讨了其物质来源和成因。研究表明:(1)如此大范围的深水沉积的硅质岩仅靠热液提供硅质来源是很难形成的,海底热液对其影响很小;(2)埃迪卡拉纪末期生物降解产物对硅质岩的形成具有重要作用,但因为缺乏可靠的古生物证据,目前还不能判定构成硅质岩的物质是否主要来源于生物体,仅能推断生物活动对硅质岩的形成有一定的影响;(3)皮园村组硅质岩主要是化学沉积的产物,二氧化硅主要来源于大陆硅酸盐矿物的风化。A series of layered black chert was deposited in the lower Yangtze region during the Ediacaran-Cambrian(E-C)transition period.In the western Zhejiang,the Diben section consists of the Piyuancun Formation,which corresponds roughly to the Liuchapo Formation or the Laobao Formation in the upper Yangtze region.The chert generally has highly organic carbon content,and is highly enriched in uranium(U),vanadium(V),molybdenum(Mo)and other redox sensitive elements.The chert,together with the black mudstone deposited in early Cambrian,is called black rock series.But there is still some debate about its genesis.The major and trace(rare earth)elements in the black chert are measured and analyzed to probe into the source and origin of the chert of the Piyuancun Formation in the western Zhejiang.The results show that:(1)It is not possible for chert deposited in such a large range of deep water to be formed only by hydrothermal sources.(2)The late Ediacaran biodegradation products have a significant impact on the formation of chert.However,it is still not possible to determine whether the materials that constitute chert is mainly derived from organisms due to the lack of reliable palaeontological evidence.We infer that biological activities exerted certain influence on the formation of chert.(3)The chert of Piyuancun Formation was mainly products of chemical deposition,and silica mainly came from the weathering of continental silicate minerals.

关 键 词：埃迪卡拉—寒武纪 硅质岩 皮园村组 主量—微量元素 

分 类 号：P595[天文地球—地球化学]